Displaying publications 1 - 20 of 97 in total

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  1. Zohdi RM, Zakaria ZA, Yusof N, Mustapha NM, Abdullah MN
    PMID: 21504052 DOI: 10.1002/jbm.b.31828
    Malaysian sea cucumber was incorporated into hydrogel formulation by using electron beam irradiation technique and was introduced as novel cross-linked Gamat Hydrogel dressing. This study investigated whether Gamat Hydrogel enhanced repair of deep partial skin thickness burn wound in rats and its possible mechanism. Wounds were treated with either Gamat Hydrogel, control hydrogel, OpSite® film dressing or left untreated. Skin samples were taken at 7, 14, 21, and 28 days post burn for histological and molecular evaluations. Gamat Hydrogel markedly enhanced wound contraction and improved histological reorganization of the regenerating tissue. Furthermore, the dressing modulated the inflammatory responses, stimulated the activation and proliferation of fibroblasts, and enhanced rapid production of collagen fiber network with a consequently shorter healing time. The level of proinflammatory cytokines; IL-1α, IL-1β, and IL-6, were significantly reduced in Gamat Hydrogel treated wounds compared with other groups as assessed by reverse transcription-polymerase chain reaction (RT-PCR). In summary, our results showed that Gamat Hydrogel promoted burn wound repair via a complex mechanism involving stimulation of tissue regeneration and regulation of pro-inflammatory cytokines. The resultant wound healing effects were attributed to the synergistic effect of the hydrogel matrix and incorporated sea cucumber.
  2. Zahari NK, Sheikh Ab Hamid S, Yusof N
    Cell Tissue Bank, 2015 Mar;16(1):55-63.
    PMID: 24647964 DOI: 10.1007/s10561-014-9438-9
    Preserved human amniotic membrane either air dried or glycerol preserved has been used effectively to treat superficial and partial thickness wounds without leaving any obvious hypertrophic scar. The preserved amnion, sterilised by ionising radiation, is known as an effective barrier for heat, fluid and protein loss while adheres nicely on wound. Air drying slightly reduced the oxygen transmission rate (OTR) of the amnion and the value significantly dropped after 15 kGy (p < 0.05). Glycerol preservation significantly reduced (p < 0.05) the OTR indicating less oxygen transmitted through the well structured cells of the amnion. Increase in the OTR with the increasing radiation doses up to 35 kGy possibly due to direct effects of radiation that resulted in large intercellular gaps. Both preservation methods significantly increased (p < 0.05) the water vapour transmission rate (WVTR). However, the low WVTR in the air dried amnion at 15 and 25 kGy was postulated due to cross-linking of collagen. Changes in the biophysical properties can be linked to direct and indirect effects of radiation on collagen bundles. The radiation dose of 25 kGy caused no adverse effect on biophysical properties hence it is still acceptable to sterilize both the air dried and the glycerol preserved amnions.
  3. Yusoff K, Razak TA, Yusof N, Rafee NM
    Int J Clin Pract, 1999 Jun;53(4):277-80.
    PMID: 10563072
    ACE inhibitors are important therapeutic agents in controlling hypertension, correcting some of its pathophysiological derangement and improving its prognosis. While there are many such agents, there may be some important differences between them. This placebo run-in, double blind, crossover study, using 24-hour ambulatory blood pressure monitoring, compares the efficacy of perindopril 4-8 mg and enalapril 10-20 mg as once daily antihypertensive agents on 32 patients. For diastolic blood pressure (DBP), perindopril had a placebo-corrected peak (P) reduction of blood pressure (BP) of -6.4 +/- 1.3 mmHg vs its placebo-corrected trough (T) of -5.2 +/- 1.7 mmHg. Enalapril had a reduction in DBP of -8.5 +/- 1.3 mmHg (P) and -5.7 +/- 1.7 mmHg (T). For systolic blood pressure (SBP), perindopril had a reduction of -7.5 +/- 1.6 mmHg (P) vs -7.3 +/- 2.2 mmHg (T) compared to enalapril with -10.8 +/- 1.6 mmHg (P) vs -8.3 +/- 2.3 mmHg (T). Placebo-corrected trough-to-peak ratio (SBP/DBP) for perindopril was 0.97/0.81 vs 0.77/0.67 for enalapril. There was no difference noted in 24-hour mean BP, area under the curve or post-dose casual BP measurements. Both perindopril and enalapril were well tolerated and the two treatment groups had similar safety profiles. Perindopril thus had a predictable and sustained blood pressure effect giving a 24-hour cover for the patient without excessive peak effect or poor trough effect.
  4. Yusof, N., Jaswir, I., Jamal, P., Jami, M.S., Octavianti, F.
    MyJurnal
    Extraction of gelatin using traditional acid-base pretreatment method has several limitations
    such as time consuming and causes serious water pollution. Chemical treatment often being used
    as an alternative process to overcome the weaknesses of the conventional method. However,
    excessive chemical elements would damage the structure of the gelatin due to its high sensitivity
    to the acid content. High Pressure Processing (HPP) is a novel and environmental friendly
    method that has been suggested to assist gelatin extraction. Pressurization during pretreatment
    could reduce the extraction time and amount of acid used. It also has a potential in enhancing the
    properties of the gelatin extract and increasing the gelatin yield. In this research, One-Factor-
    at-Time (OFAT) and optimization study were done to determine the optimum parameters for
    extraction of gelatin assisted by HPP from red tilapia skin. Four parameters; applied pressure,
    pressure holding time, ratio of acid to skin and extraction time have been selected for the OFAT
    design and concentration of the gelatin extract and percentage of yield gelatin were evaluated.
    From OFAT, optimum technical parameters for response surface optimization design were 250
    MPa pressure, 7.5 ml of acid to 1 g of skin and 12 hours extraction time. Pressure holding
    time was fixed for 10 min. FCCCD has been used for optimization study. Results from the
    data shows that the optimum conditions for gelatin extraction from red tilapia skin were 250
    MPa for pressure, 10 min of pressure holding time, 7.5 ml of acid for 1 g of skin and 12 hours
    of extraction time while the maximum concentration and yield were 19.51 mg/ml and 32.04%
    (320.4 mg/g), respectively. These findings proved that HPP could increase the concentration
    and the yield of the gelatin while reducing the chemical waste and shortening the extraction
    process.
  5. Yusof NNM, Rutherford KMD, Jarvis S, Valente L, Dwyer CM
    Animal, 2023 Nov;17(11):101006.
    PMID: 37897868 DOI: 10.1016/j.animal.2023.101006
    It is common in many countries for sheep to be housed during winter from mid-gestation until lambing to protect ewes and lambs from adverse conditions and improve late gestation nutritional management. Keeping ewes indoors, however, has its own challenges as the animals may be mixed with unfamiliar conspecifics, have limited floor and feeding space, experience changes to their diet and increased handling by humans. Therefore, the objective of this study was to investigate the effect of variation in housing management (space allowance and social stability) on the behaviour and hypothalamic-pituitary-adrenal (HPA) axis responses of pregnant ewes from mid-to-late gestation (weeks 11-18 of pregnancy). Seventy-seven ewes (41 primiparous, 36 multiparous) were divided into two groups: 'Control' and 'Restricted space and mixed' (RS-Mix), where RS-Mix ewes were allocated half the amount of space (1.27 vs 2.5 m2 for RS-Mix and Control, respectively) and feedface (concentrate feeder space) allowance (36 vs 71 cm per ewe) given to the Control group and were also subjected to two social mixing events. Aggressive behaviour at the feedface and time spent standing, lying, walking, feeding and ruminating were recorded and faecal samples were collected for assessment of faecal glucocorticoid metabolite (FGM) concentrations. Higher aggression was observed in RS-Mix ewes during the first week of observation (P = 0.044), which gradually declined to the same level as Control ewes by the end of the study (P = 0.045). RS-Mix ewes were significantly less likely to be able to freely join the feedface compared to Controls (P = 0.022). No other significant treatment effects on aggressive behaviour or FGM during gestation were found. RS-Mix ewes displayed significantly higher ruminating behaviour at week 18 of gestation compared to Control ewes (P 
  6. Yusof NM, Fadzli AS, Azman WS, Azril MA
    Med J Malaysia, 2016 04;71(2):47-52.
    PMID: 27326940 MyJurnal
    INTRODUCTION: The understanding of the skin's vascular anatomy has improved in the last decade. It has lead to technique modification such as the staged procedure in performing sural flaps and improvement in the flap survival rate. The aim of this study was to evaluate the acute vascular complications (flap necrosis or congestion) of 29 patients who underwent distal base sural flap for coverage of wound around the ankle.

    METHODS: Twenty-four males and five females with a mean age of 37.1 years old underwent sural flap surgery to cover wounds at around the ankle. There were 12 cases of open fracture, five infected fractures, four spoke injuries, four degloving injuries and four diabetic foot ulcers. Twentythree cases were done as a single stage procedure while six as a two-stage procedure. The flaps were tunnelled under the skin in three cases.

    RESULTS: Twenty one flaps healed uneventfully, seven acute vascular complications occur in a single stage group: five developed partial necrosis, one had congestion with epidermolysis, and one had complete flap necrosis. Complications were treated by dressing or skin grafting and only one required a repeat flap surgery.

    CONCLUSIONS: Acute vascular complications may be minimised when sural flap is done in stages for elderly, diabetic, smokers and/or patients with large wound around the ankle. Even if the flap appears necrotic, the underlying structure may still be covered as the fasciosubcutaneous layer of the flap may still survive.
  7. Yusof NH, Foo KY, Hameed BH, Hussin MH, Lee HK, Sabar S
    Int J Biol Macromol, 2020 Aug 15;157:648-658.
    PMID: 31790734 DOI: 10.1016/j.ijbiomac.2019.11.218
    Chitosan-polyethyleneimine with calcium chloride as ionic cross-linker (CsPC) was synthesized as a new kind of adsorbent using a simple, green and cost-effective technique. The adsorption properties of the adsorbent for Acid Red 88 (AR88) dye, as a model analyte, were investigated in a batch system as the function of solution pH (pH 3-12), initial AR88 concentration (50-500 mg L-1), contact time (0-24 h), and temperature (30-50 °C). Results showed that the adsorption process obeyed the pseudo-first order kinetic model and the adsorption rate was governed by both intra-particle and liquid-film mechanism. Equilibrium data were well correlated with the Freundlich isotherm model, with the calculated maximum adsorption capacity (qm) of 1000 mg g-1 at 30 °C. The findings underlined CsPC to be an effective and efficient adsorbent, which can be easily synthesized via one-step process with promising prospects for the removal of AR88 or any other similar dyes from the aqueous solutions.
  8. Yusof N, Hassan MA, Yee PL, Tabatabaei M, Othman MR, Mori M, et al.
    Waste Manag Res, 2011 Jun;29(6):602-11.
    PMID: 21447612 DOI: 10.1177/0734242X10397581
    Nitrification of mature sanitary landfill leachate with high-strength of N-NH(4) + (1080-2350 mg L(-1)) was performed in a 10 L continuous nitrification activated sludge reactor. The nitrification system was acclimatized with synthetic leachate during feed batch operation to avoid substrate inhibition before being fed with actual mature leachate. Successful nitrification was achieved with an approximately complete ammonium removal (99%) and 96% of N-NH(4) + conversion to N-NO(-) (3) . The maximum volumetric and specific nitrification rates obtained were 2.56 kg N-NH(4) (+) m(-3) day(-1) and 0.23 g N-NH(4) ( +) g(-1) volatile suspended solid (VSS) day(-1), respectively, at hydraulic retention time (HRT) of 12.7 h and solid retention time of 50 days. Incomplete nitrification was encountered when operating at a higher nitrogen loading rate of 3.14 kg N-NH(4) (+) m(-3) day(-1). The substrate overloading and nitrifiers competition with heterotrophs were believed to trigger the incomplete nitrification. Fluorescence in situ hybridization (FISH) results supported the syntrophic association between the ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria. FISH results also revealed the heterotrophs as the dominant and disintegration of some AOB cell aggregates into single cells which further supported the incomplete nitrification phenomenon.
  9. Yusof N, Haraguchi A, Hassan MA, Othman MR, Wakisaka M, Shirai Y
    Waste Manag, 2009 Oct;29(10):2666-80.
    PMID: 19564103 DOI: 10.1016/j.wasman.2009.05.022
    Since landfilling is the common method of waste disposal in Malaysia, river water is greatly exposed to the risk of contamination from leachate unless proper leachate management is carried out. In this study, leachates from three different types of landfills, namely active uncontrolled, active controlled and closed controlled, were characterized, and their relationships with river water chemistry were examined monthly for a year. The influence of leachate on river water chemistry from each type of landfill depended on many factors, including the presence of a leachate control mechanism, leachate characteristics, precipitation, surface runoff and the applied treatment. The impact of leachate from an active uncontrolled landfill was the highest, as the organic content, NH(4)(+)-N, Cd and Mn levels appeared high in the river. At the same time, influences of leachate were also observed from both types of controlled landfills in the form of inorganic nitrogen (NH(4)(+)-N, NO(3)(-)-N and NO(2)(-)-N) and heavy metals (Fe, Cr, Ni and Mn). Improper treatment practice led to high levels of some contaminants in the stream near the closed controlled landfill. Meanwhile, the active controlled landfill, which was located near the coastline, was exposed to the risk of contamination resulting from the pyrite oxidation of the surrounding area.
  10. Yusof N, Morales Pedraza J
    Cell Tissue Bank, 2009 May;10(2):115-7.
    PMID: 18581259 DOI: 10.1007/s10561-008-9085-0
    The IAEA was instrumental in developing the first Malaysian tissue bank at University Hospital of Universiti Sains Malaysia (HUSM), Kubang Kerian, Kelantan in early 1990s and it was officiated as National Tissue Bank in 1994. Up to date, 38 government and private hospitals have received a supply from the bank. Bone allografts in term of bone chips, morsalised bone and long bones are procured from Malaysian donors. Almost thirty students from Malaysia graduated in the training courses carried out in Singapore since 1998 at regional and interregional levels. Organ donation is more readily accepted by the public at the moments, perhaps due to the vast promotion and advertisement given by the local newspapers and other media, but gradually tissue donation is catching up as well.
  11. Yusof N, Hamid N, Ma ZF, Lawenko RM, Wan Mohammad WMZ, Collins DA, et al.
    Gut Pathog, 2017;9:75.
    PMID: 29255490 DOI: 10.1186/s13099-017-0224-7
    Background: After an environmental disaster, the affected community is at increased risk for persistent abdominal pain but mechanisms are unclear. Therefore, our study aimed to determine association between abdominal pain and poor water, sanitation and hygiene (WaSH) practices, and if small intestinal bacterial overgrowth (SIBO) and/or gut dysbiosis explain IBS, impaired quality of life (QOL), anxiety and/or depression after a major flood.

    Results: New onset abdominal pain, IBS based on the Rome III criteria, WaSH practices, QOL, anxiety and/or depression, SIBO (hydrogen breath testing) and stools for metagenomic sequencing were assessed in flood victims. Of 211 participants, 37.9% (n = 80) had abdominal pain and 17% (n = 36) with IBS subtyped diarrhea and/or mixed type (n = 27 or 12.8%) being the most common. Poor WaSH practices and impaired quality of life during flood were significantly associated with IBS. Using linear discriminant analysis effect size method, gut dysbiosis was observed in those with anxiety (Bacteroidetes and Proteobacteria, effect size 4.8), abdominal pain (Fusobacteria, Staphylococcus, Megamonas and Plesiomonas, effect size 4.0) and IBS (Plesiomonas and Trabulsiella, effect size 3.0).

    Conclusion: Disturbed gut microbiota because of environmentally-derived organisms may explain persistent abdominal pain and IBS after a major environmental disaster in the presence of poor WaSH practices.

  12. Yusof N, Abdullah Tahir A, Riyadi FA, Ahmad Sabri NS, Md Akhir FN, Othman N, et al.
    Microbiol Resour Announc, 2020 Jan 30;9(5).
    PMID: 32001560 DOI: 10.1128/MRA.01332-19
    Streptomyces spp. are bacteria that are responsible for the degradation of aromatic compounds and produce secondary metabolites. Here, we present a complete genome sequence of Streptomyces sp. strain S6, which was isolated from an oil palm plantation, with a 7.8-Mbp liner chromosome, a GC content of 72%, and 4,266 coding sequences.
  13. Yusof N
    Cell Tissue Bank, 2018 Jun;19(2):175-186.
    PMID: 29022196 DOI: 10.1007/s10561-017-9651-4
    Under the auspices of the IAEA tissue banking programme on "Radiation Sterilisation of Tissue Graft" conducted from 1985 to 2004, many scientists and surgeons were involved in various regional research and development (R&D) projects mainly in dealing with radiation dose selection, radiation effects on human tissues and quality system in radiation sterilisation. New findings on radiation effects, tissue processing and preservation were shared during the regional and interregional meetings and workshops. Many tissue banks started to use radiation (25 kGy) to sterilize tissue grafts for tissue safety and efficacy and still continue to use it. The IAEA Code of Practice for Radiation Sterilization of Tissues Allografts developed in 2007 offered simpler methods to conduct radiation dose setting and dose validation experiments for tissue grafts. Advances in dose selection and dose mapping are continued under the quality management system when banks need to be certified to continue their operation. The combination of good tissue processing and preservation as well as good radiation practice will ensure the tissue products are properly sterilised thus safe and of high quality. Experience in meeting challenges in using radiation sterilisation and achievements reported by the tissue bankers are shared here.
  14. Yousuf R, Abdul Aziz S, Yusof N, Leong CF
    J Med Case Rep, 2012;6:71.
    PMID: 22348809 DOI: 10.1186/1752-1947-6-71
    Hemolytic disease of the fetus and newborn is most commonly caused by anti-D alloantibody. It is usually seen in Rhesus D (RhD)-negative mothers that have been previously sensitized. We report here a case of hemolytic disease of the fetus and newborn in a newborn baby caused by anti-D and anti-S alloantibodies, born to a mother who was RhD negative, but with no previous serological evidence of RhD alloimmunization.
  15. Yousuf R, Abdul Aziz S, Yusof N, Leong CF
    Indian J Hematol Blood Transfus, 2013 Jun;29(2):65-70.
    PMID: 24426338 DOI: 10.1007/s12288-012-0155-x
    Red blood cell alloimmunization is a common complication among the transfusion recipients. In Malaysia, multiple ethnicity causes genetic heterogeneity among the population which in turn can cause a wide variation of antibody. The objective of this study was to analyse the red cell alloantibody detected during the pre-transfusion testing. This was a cross-sectional study done in the blood bank of Universiti Kebangsaan Malaysia Medical Centre during the period of January-December 2010. The data was retrieved from the hospital laboratory information system. A total of 24,263 patients' blood samples were subjected for pre-transfusion testing. Antibody screening was done using an indirect antiglobulin test method. The positive samples were further identified for antibody specificity. Antibody screening tests were positive in 184 patients out of 24,263 samples with the incidence of 0.76 %. Autoantibodies and alloantibodies were detected in 39/184 (21.2 %) and 140/184 (76.1 %) of the patients respectively. In five patients (2.7 %) the antibody specificity remained undetermined. Total 161 alloantibodies were identified. The suspected Anti-Mia alloantibody was observed most frequently (49/161, 30.4 %) followed by anti-E (30/161, 18.6 %) and anti-D (22/161, 13.7 %). Anti-E and anti-c were the most common combination of multiple alloantibodies. In view of the high incidence of suspected Anti-Mia antibodies, more efforts are needed to look into the techniques for confirmation of the Anti-Mia antibodies. Besides that, we suggested that all multiply transfused patients should be phenotyped for the Rh system and to supply Rh phenotype specific blood in order to limit alloimmunization.
  16. Yousuf R, Abdul Aziz S, Yusof N, Leong CF
    Indian J Hematol Blood Transfus, 2014 Sep;30(3):208-10.
    PMID: 25114411 DOI: 10.1007/s12288-012-0211-6
    We report a 47-year-old Malay lady, para 4 + 1, with known medical history of hypertension whom presented at Emergency Department with severe anaemia, most likely secondary to menorrhagia caused by uterine fibroids. Her haemoglobin was 5.5 g/dl and she was transfused with three units of packed cell without any adverse reaction, her haemoglobin level increased to 9.8 g/dl. She was then planned for total abdominal hysterectomy and bilateral salpingo-oophorectomy later. Four months later when she came for the elective surgery, her pre transfusion investigations showed blood group as B Rh D positive, with a probable R1R1 phenotype. Her antibody screening was positive in all the three panel cells. Further testings showed a negative Direct Coomb's test and negative autocontrol, antibody identification showed pan-agglutination reaction on all 11 panel cells with enzyme enhancement. Patient's red cell phenotype was Jk(a-b-). Anti-Jk3 was suspected and further confirmed in the reference laboratory by phenotyping as well as negative urea lysis test. This case report highlights an extremely rare but clinically significant anti-JK3 antibody detected during pretransfusion testing. This phenotype is rare in the white population, more commonly seen in various polynesians. Increased awareness among the blood bank personnel regarding the variability of the blood group phenotype and the capricious nature of the Kidd antibodies may contribute to the better management of these patients.
  17. Yong WL, Yusof N, Ithnin A, Shuib S, Tumian R, Yousuf R, et al.
    Malays J Pathol, 2020 Dec;42(3):469-476.
    PMID: 33361731
    INTRODUCTION: Mixed phenotype acute leukaemia (MPAL) is a rare entity of acute leukaemia.

    CASE REPORT: Here we report a case of a 39-year-old lady, with an incidental finding of hyperleukocytosis (white blood cells count: 139.2 x 109/L). Her peripheral blood film revealed 36% of blasts and a bone marrow aspiration showed 53% of blasts. Immunophenotyping showed a population of blasts exhibiting positivity of two lineages, myeloid lineage and B-lymphoid lineage with strong positivity of CD34 and terminal deoxynucleotidyl transferase (Tdt). A conventional karyotyping revealed the presence of Philadelphia chromosome. She was diagnosed with MPAL with t(9,22), BCR ABL1, which carried a poor prognosis. She was treated with acute lymphoblastic leukaemia (ALL) chemotherapy protocol coupled with a tyrosine kinase inhibitor and was planned for an allogeneic stem cells transplant.

    CONCLUSION: This MPAL case was diagnosed incidentally in an asymptomatic patient during medical check-up. We highlight this rare case report to raise the awareness about this rare disease. Understanding the pathogenesis of the disease with the underlying genes responsible for triggering the disease, uniform protocols for diagnosis and targeted treatment will help for proper management of these patients.

  18. Yong MW, Yusof N, Rampal L, Arumugam M
    J Hand Surg Asian Pac Vol, 2017 Dec;22(4):484-489.
    PMID: 29117832 DOI: 10.1142/S021881041750054X
    BACKGROUND: Palmaris Longus is being widely used in reconstructive, plastic and cosmetic surgeries due to its long tendon. It is the most readily available source for tendon grafting. The objective of this study was to determine the prevalence of absence of Palmaris Longus and its association with gender, hand dominance and absence of FDS (flexor digitorum superficialis) tendon to little finger among Malay population.

    METHODS: An analytical cross sectional study design was used and a self-administered proforma was distributed for data collection. 1239 Malay secondary school children in Putrajaya were tested for absence of Palmaris Longus using Schaffer's test. 4 additional tests namely Thompson's test, Mishra's test I, Mishra's test II and Pushpakumar's 'two-finger sign' method were used to confirm its absence in respondents with negative Schaffer's test. Function of Flexor Digitorum Superficialis tendon to little finger was determined by flexing PIP of little finger while hyperextend the other fingers.

    RESULTS: The prevalence of absence of Palmaris Longus was 11.7%. Left side absence of Palmaris Longus was much common. There was a significant association between absence of Palmaris Longus with gender in which female had higher prevalence of absence of Palmaris Longus than male.

    CONCLUSIONS: In conclusion, the prevalence of absence of Palmaris Longus in Malay population was lower than Indian but higher than Chinese population. Females had higher prevalence of absence of Palmaris Longus and no association can be found with hand dominance and absence of Flexor Digitorum Superficialis tendon to little finger.

  19. Yang Harmony TC, Yusof N, Ramalingam S, Baharin R, Syahrom A, Mansor A
    Clin Orthop Relat Res, 2022 Feb 01;480(2):407-418.
    PMID: 34491235 DOI: 10.1097/CORR.0000000000001968
    BACKGROUND: Gamma irradiation, which minimizes the risk of infectious disease transmission when human bone allograft is used, has been found to negatively affect its biomechanical properties. However, in those studies, the deep-freezing temperature during irradiation was not necessarily maintained during transportation and sterilization, which may have affected the findings. Prior reports have also suggested that controlled deep freezing may mitigate the detrimental effects of irradiation on the mechanical properties of bone allograft.

    QUESTION/PURPOSE: Does a controlled deep-freezing temperature during irradiation help preserve the compressive mechanical properties of human femoral cortical bone allografts?

    METHODS: Cortical bone cube samples, each measuring 64 mm3, were cut from the mid-diaphyseal midshaft of five fresh-frozen cadaver femurs (four male donors, mean [range] age at procurement 42 years [42 to 43]) and were allocated via block randomization into one of three experimental groups (with equal numbers of samples from each donor allocated into each group). Each experimental group consisted of 20 bone cube samples. Samples irradiated in dry ice were subjected to irradiation doses ranging from 26.7 kGy to 27.1 kGy (mean 26.9 kGy) at a deep-freezing temperature below -40°C (the recommended long-term storage temperature for allografts). Samples irradiated in gel ice underwent irradiation doses ranging from 26.2 kGy and 26.4 kGy (mean 26.3 kGy) in a freezing temperature range between -40°C and 0°C. Acting as controls, samples in a third group were not subjected to gamma irradiation. The mechanical properties (0.2% offset yield stress, ultimate compression stress, toughness, and the Young modulus) of samples from each group were subsequently evaluated via axial compression loading to failure along the long axis of the bone. The investigators were blinded to sample group during compression testing.

    RESULTS: The mean ultimate compression stress (84 ± 27 MPa versus 119 ± 31 MPa, mean difference 35 [95% CI 9 to 60]; p = 0.005) and toughness (3622 ± 1720 kJ/m3 versus 5854 ± 2900 kJ/m3, mean difference 2232 [95% CI 70 to 4394]; p = 0.009) of samples irradiated at a higher temperature range (-40°C to 0°C) were lower than in those irradiated at deep-freezing temperatures (below -40°C). The mean 0.2% offset yield stress (73 ± 28 MPa versus 109 ± 38 MPa, mean difference 36 [95% CI 11 to 60]; p = 0.002) and ultimate compression stress (84 ± 27 MPa versus 128 ± 40 MPa, mean difference 44 [95% CI 17 to 69]; p < 0.001) of samples irradiated at a higher temperature range (-40°C to 0°C) were lower than the nonirradiated control group samples. The mean 0.2% offset yield stress (73 ± 28 MPa versus 101 ± 28 MPa, mean difference 28 [95% CI 3 to 52]; p = 0.02; effect size = 1.0 [95% CI 0.8 to 1.2]) of samples irradiated at higher temperature range (-40°C to 0°C) were no different with the numbers available to those irradiated at deep-freezing temperature. The mean toughness (3622 ± 1720 kJ/m3 versus 6231 ± 3410 kJ/m3, mean difference 2609 [95% CI 447 to 4771]; p = 0.02; effect size = 1.0 [95% CI 0.8 to 1.2]) of samples irradiated at higher temperature range (-40°C to 0°C) were no different with the numbers available to the non-irradiated control group samples. The mean 0.2% offset yield stress, ultimate compression stress, and toughness of samples irradiated in deep-freezing temperatures (below -40°C) were not different with the numbers available to the non-irradiated control group samples. The Young modulus was not different with the numbers available among the three groups.

    CONCLUSION: In this study, maintenance of a deep-freezing temperature below -40°C, using dry ice as a cooling agent, consistently mitigated the adverse effects of irradiation on the monotonic-compression mechanical properties of human cortical bone tissue. Preserving the mechanical properties of a cortical allograft, when irradiated in a deep-freezing temperature, may have resulted from attenuation of the deleterious, indirect effects of gamma radiation on its collagen architecture in a frozen state. Immobilization of water molecules in this state prevents radiolysis and the subsequent generation of free radicals. This hypothesis was supported by an apparent loss of the protective effect when a range of higher freezing temperatures was used during irradiation.

    CLINICAL RELEVANCE: Deep-freezing temperatures below -40°C during gamma irradiation may be a promising approach to better retain the native mechanical properties of cortical bone allografts. A further study of the effect of deep-freezing during gamma radiation sterilization on sterility and other important biomechanical properties of cortical bone (such as, tensile strength, fracture toughness, and fatigue) is needed to confirm these findings.

  20. Yaakob, K.I., Mohd Shafri, M.A., Mohd Yusof, N., Mohamed, F.
    MyJurnal
    Biofilm complicates osteomyelitis as there is antibiotic resistance and toxicity involved. In order to overcome the challenges of current treatment, gentamicin, the current antibiotic of choice for osteomyelitis, is fused with Nigella sativa oil to form an emulsion. Its efficacy as anti-biofilm agent is assessed using confocal laser scanning microscope (CLSM) against different strains of biofilm-producing Staphylococcus aureus. These strains of S.aureus were first allowed to express biofilm before being exposed for 24 hours to the emulsion with (0.1% (w/v) gentamicin; 40.2% (v/v) N.sativa. Later, the emulsion was removed and the biofilm was stained with fluorescence staining. The slides were viewed under CLSM at 100 times resolution. 3D images of biofilm were reconstructed, using Image J software, to measure the thickness of biofilm and viability of bacteria cells. Results revealed that the emulsion significantly reduced biofilm thickness compared to gentamicin and N.sativa alone in all strains of S.aureus (Tukey’s test p < 0.05). The emulsion was also able to produce more than 80% and 15% surface percentage (%) of non-viable (dead) bacteria in the sensitive and resistant strain, respectively, at a significant level when compared to gentamicin and N.sativa (Tukey’s test p < 0.05). As a conclusion, this new fusion of gentamicin-N.sativa may be effective towards the biofilm of S.aureus, and can be developed further as a new promising anti-biofilm agent in osteomyelitis.
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